Comparison of electric charge and mass Characters Electric ass Charge (gravitational) Property Positive/neg Only ative positive Interaction yes yes Quantization yes no Lozents variation Invariance covariance conservation yes E=mc2 Different definition no Gravitation inertialCharacters Electric Charge Mass (gravitational) Property Positive/neg ative Only positive Interaction yes yes Quantization yes no Lozents variation Invariance covariance conservation yes E=mc2 Different definition no Gravitation al/inertial Comparison of electric charge and mass